A former Houston police officer pleaded guilty Tuesday to running drug money as a courier for an organization that laundered as much as $27 million collected from around the United States, then pumped through Houston and on to Mexico.

Anthony Foster, 47, faces up to 25 years in federal prison without parole for his role in the conspiracy, but could serve less time if he cooperates with authorities still looking for members of the organization, including the boss, who are believed to be in Mexico.

U.S. District Judge Lee Rosenthal warned Foster and co-defendant Sarah Combs, 48, a former office manager who also pleaded guilty Tuesday, that she is not obligated to show leniency when they are sentenced in May.

"If the sentence you get is heaver than you expect, you understand that you are stuck with it," Rosenthal cautioned before the pleas were final. "You cannot get out of it."

Combs faces up to five years.

The case exposed an enterprise that operated out of a simple office tucked away behind an auto collision shop on Westheimer in far-west Houston.

Money was brought to Houston in bulk, then transferred between financial institutions to make the jump from the United States to Mexico, according to an indictment.

Authorities have not said why they believe the money was connected to drugs.

Foster is a Marine Corps veteran, as is his nephew, Willie Whitehurst, who is also scheduled to plead guilty, according to court records.

In the legitimate business world, Whitehurst advertised his services as a courier, bodyguard and bounty hunter.

Foster was driving on the North Freeway last year with more than $350,000 stashed in what looked like a case of "Kentucky Deluxe" whiskey when he was stopped by police.

He resigned from the Houston Police Department in 2009 after 15 years on the force, and while under investigation for taking a bribe.

He later pleaded guilty to a misdemeanor charge of taking money from an undercover officer posing as a motorist and received deferred adjudication.

After Foster left the HPD, he made $1,000 a week as a driver running errands, such as dropping children off at school, said his lawyer, Ed Mallett.

"He was never compensated above his salary," Mallett said. The money was earned on the books, and Social Security was withheld, he said.

Others in the organization are fugitives and as many as five of them are believed to be hiding in Mexico, including Luis Ojeda, a Mexican citizen who was contacted there by the Houston Chronicle last year and proclaimed his innocence.

"You have thrown me a curve ball. My God, what a mess," said Ojeda, the owner of an energy-services company in Mexico that once operated a money-exchange business that converted dollars to pesos.